Sort tray icons that belong to the same process

Since Windows 7 tray icons can be sorted with drag and drop. But if an application has multiple tray icons or multiple instances of the same application are running these icons can only be moved as a group.
Please make it possible to sort the icons within these groups. For example in the same way as it is possible to move grouped items with the option "Drag within/between groups using right mouse button".
The sorting doesn't necessarily have to be saved in the registry as this could be very complicated.